1. Technical Field
The present invention relates to a liquid droplet ejection head and a liquid droplet ejection apparatus.
2. Related Art
In a liquid droplet ejection apparatus such as an ink jet printer, a liquid droplet ejection head is provided for ejecting liquid droplets. One known liquid droplet ejection head is provided with an ink chamber (cavity) which stores an ink therein and communicates with a nozzle for ejecting the ink in the form of liquid droplets, and a piezoelectric element for driving which deforms a wall surface of the ink chamber.
In such a liquid droplet ejection head, a part of the ink chamber (a vibration plate) is deformed by expanding and contracting the piezoelectric element for driving. By doing this, the volume of the ink chamber is changed, whereby the liquid droplets of the ink are ejected through the nozzle.
In the meantime, such a liquid droplet ejection head is assembled by bonding a nozzle plate in which the nozzles are formed to a substrate which defines the ink chamber with an adhesive.
However, it is very difficult to precisely control a supply amount of the adhesive when supplying the adhesive between the nozzle plate and the substrate. Therefore, the amount of the adhesive to be supplied cannot be controlled to be uniform, and thus, a distance between the nozzle plate and the substrate becomes uneven. Accordingly, uniform volumes cannot be obtained among a plurality of ink chambers provided in a liquid droplet ejection head, or uniform volumes of ink chambers cannot be obtained among liquid droplet ejection heads. Further, a distance between the liquid droplet ejection head and a printing medium such as printing paper becomes uneven. Further, the adhesive may disadvantageously run out of the bond area. These problems deteriorate the dimensional accuracy of the liquid droplet ejection head, resulting in deteriorating the printing quality of the ink jet printer.
Further, the adhesive is exposed to an ink stored in the ink chamber for a long period of time. When the adhesive is exposed to the ink in this manner, the adhesive is altered or deteriorated by an organic component contained in the ink. Accordingly, the liquid tightness of the ink chamber may be lowered or a component contained in the adhesive may be dissolved in the ink.
On the other hand, a method in which respective members constituting a liquid droplet ejection head are bonded by a solid bonding method is also known.
The solid bonding method is a method in which the respective members are directly bonded to one another without interposing an adhesive layer formed of an adhesive or the like therebetween. Examples of such a solid bonding method include a diffusion bonding method, a silicon direct bonding method, and an anodic bonding method (see, for example, JP-A-2007-62082).
However, the solid bonding method has the following problems: the materials of the members which can be bonded are limited; a heat treatment at a high temperature (e.g., about 700 to 800° C.) is required in a bonding process; an atmosphere in the bonding process is limited to a reduced pressure atmosphere; and it is difficult to partially bond some regions to each other.